Switch relay for use in electric motors



June 14, 1966 c. E. LINKOUS I 3,256,402

SWITCH RELAY FOR USE IN ELECTRIC MOTORS Filed Jan. 2, 1964 5Sheets-Sheet 1 INVENTOR. C/ow's E. L frz/foas,

June 14, 1966 c. E. LINKOUS 3,256,402

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swxwca RELAY FOR USE IN ELECTRIC MOTORS Filed Jan. 2, 1964 5Sheets-Sheet 3 it-ms ws M5 INVENTOR.

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BWAmM United States Patent SWITCH RELAY FOR USE IN ELECTRIC MOTORSClovis E. Linkous, Fort Wayne,.Ind., assignor to General ElectricCompany, a corporation of New York Filed Jan. 2, 1964, Ser. No. 335,284.12 Claims. (Cl. 200-87) These relays customarily include a corestructure and a cooperating moveable armature which defines a variablemagnetic air gap with the core and carries means for actuating themovable contact of the relay. Unfortunately, the relays are usuallyrather complicated and costly in design to achieve a longevity over100,000 cycles of operation, far less than the number of cycles requiredto approach the life expectancy of the motor in which they are used.These relays normally require mechanical impact elements for separatingthe movable and stationary contacts in an attempt to prevent theoccurrence of contact welding. Further, the more satisfactory prior artrelays incorporate certain close toleranoe parts; e.g., the mechanicalimpact element and armatures, in an attempt to attain a life expectancyof at least 100,000 operations. Such relays may even include anexpensive and complicated calibration system in an effort to obtain acontrolled movement of the armature which does not vary substantiallybetween one operation and the next. Another problem with this type ofrelay is the noise it produces during operation which is particularlynoticeable and objectionable when the relay is employed in motors usedfor domestic applications, such as in typewriters, appliances, and thelike.

It is therefore a general object of the present invention to provide animproved switch relay especially adapted for use in electric motors andit is a more specific object to provide such relay which overcomes thedeficiencies mentioned above.

It is still another object of the invention to provide a relativelyinexpensive relay which incorporates easily assembled components, isquiet in operation, and provides a positive and consistently uniformmotion of the movable switch contact.

It is another object of the invention to provide a switch relay which iscompact and simple in design, rugged in construction, does not requireclose toleranced mechanical impact elements, yet is capable of well over1,000,000 cycles of trouble-free and generally uniform operation.

In carrying out the objects of the present invention in one form, Iprovide a dynamoelectric machine having start and main windings with animproved switch relay for controlling the circuit of the start winding.The relay includes a core formed of magnetic material having at leasttwoupstanding leg sections joined together at one end by a yoke section.One of the ends of the legs, remote from the yoke section, pivotallymounts an armature for swinging its free end toward and away from theother leg sections. At least one of the relay legs accommodates a coilwhich is adapted to be energized during operation of the motor foractuating the armature. A generally U-shaped spring is connected undercompression between the free end of the armature and a support forbiasing the free end of the armature away from ice the relay core. Astationary switch contact is spaced from the side of the armature remotefrom the core,.with a second contact being movably carried by acantilever spring which normally biases the second contact intoengagement with the first contact to provide a normally closed set ofcontacts.

The armature and cantilever spring are connected together for movementby a lost motion connection such that both springs apply a bias to thearmature when the contacts are in a nonengaging relation, with thesprings together defining a net negative spring constant, but only theU-shaped spring applies a bias to the armature once the contacts areclosed. The relay also includes calibrating means which simultaneouslyregulates the bias of the U-shaped spring and the magnetic air gapbetween the armature and the core. A small change in the calibrating airgap has a large controlling afiect on the voltage at which the armatureis pulled down toward the core.

When the contacts are in the closed position, the lost motion connectionpermits unimpeded movement between the armature and the second contactfrom the fully open position of the armature to the point at which thearmature makes a firm connection with the cantilever spring whichcarries the movable contact. Thus, when the coil is energized and thearmature overcomes the bias of the U-shaped springs and moves from thefully open to firm connection positions, the armature engages thecantilever spring with an impact to separate the contacts with a suddenmotion. This engagement is achieved due to the momentum imparted to thearmature before engagement and serves to breakrwelds which might occurin the switch contacts.

The subject matter which I regard as my invention, is particularlypointed out and distinctly claimed in the concluding portion of thisspecification. My invention itself, however, both as' to itsorganization and method of operation, together with further objects andadvantages thereof may best be understood by reference to the followingdescription taken in connection with the accompanying drawing.

In the drawing:

FIG. 1 is a side elevational view of a normally closed switch relayassembly embodying one form of my invention;

FIG. 2 is a view taken along line 2-2 in FIG. 1;

FIG. 3 is an enlarged, fragmentary view of a portion of the relayassembly of FIG. 1, showing the relay components intheir respectivepositions at the instant that the switch contacts either become engagedor just prior to their separation, depending upon the direction ofarmature travel;

FIG. 4 is a view similar to FIG. 3 revealing the same components, withthe armature in the fully closed position and the contacts in the opencontact position;.

FIG. 5 is a schematic diagram showing the relay assembly of FIG. 1connected in the start winding circuit of a single phase split phaseelectric motor;

FIG. 6 is a graphic presentation of the forces exerted on the relayarmature by the relay spring system of the relay assembly of FIG. 1plotted against the distance across the magnetic air gap at the end ofthe armature remote for its pivot;

FIG. 7 is a side elevational view of a switch relay assemblyincorporating another form of my invention;

FIG. 8 is a view taken along line 8-8 in FIG. 7 and;

FIG. 9 is a view taken along line 99 in FIG. 7.

Referring now to the drawings in more detail, and in particular to theembodiment illustrated by FIGS. 1-6 inclusive, one form of my improvedswitch relay is .generally identified by character numeral 10. The relayis provided with an E-shaped core structure 11 formed of magneticmaterial such as iron or steel, having three spaced apart magnetizableleg sections 12, 13, and 14 integrally joined at one end by an elongatedmagnetic yoke section 15. Outermost leg section 12 has its free end 12a,remote from yoke section 15, extending above free ends 13a and 14a ofthe remaining two leg sections (as viewed in FIG. 1) and is formed withmeans for pivotally mounting one end of an elongated armature assemblyor mechanism, denoted by numeral 21. This pivotal connection takes theform of an enlanged, generally U-shaped notch 16, furnished in the edgeof leg portion 12a which faces middle leg 13. The armature mechanism 21has a rectangular slot 22 (FIG. 2) with the smaller size wall 23 of theslot being received within notch 16 for providing a fulcrum pivotalsupport of mechanism 21 In order to facilitate both the pivotal actionof mechanism 21 and the assembly of the parts, the longer wall of slot22 is dimensionally greater than the width across leg portion 12a abovenotch 16.

Mounted on the middle leg 13 of core 11 is an excitation winding or coil18 which is adapted to be energized in a manner to be described indetail hereinafter. The coil is suitably insulated from the core as byMylar, fiber board, or other electrical insulation. A shading coil 20incircles outermost leg section 14, remote from the pivot of thearmature, and functions to delay a change of flux through the shaded legsection in the well-known way.

Turning now more specifically to the illustrated construction ofarmature mechanism 21, it is provided with a magnetizable elongatedelement 24 which has its free end 25 arranged to swing toward and awayfrom free end 14a of leg section 14 in response to the magnetization ofthe core by coil 18 and defines a magnetic air 'gap therewith.

electrically conducting, spring arm or blade 29 which applies acontinuous bias to contact 28 toward the normally closed engagingposition shown in FIG. 1. Arm 29 has its end 31 suitably secured as by arivet 40 (FIG. 2) onto a support best seen in FIG. 1. The support isgenerally indicated by numeral 30 and for purposes of disclosure is ofthe type disclosed and claimed in my copending and concurrently filedpatent application, Serial No. 335,243 filed January 2, 1965. Asdescribed in that application the support is a single piece, molded ofthermoresponsive material. In the present exemplification it serves tomount core 11 of the relay as well as switch contacts 26 and 28 within achamber 32.

Returning once again to the description of armature mechanism 21, agenerally U-shaped toggle spring 35 is employed to bias the free end 25of the assembly away from core leg section 14. In the first embodiment,shown in FIGS. 1-6, this is achieved by securing a metal bracket 36 onthe top (as viewed in FIG. 1) of element 24 as by a number of spotwelds, and bending bracket extension 37 downwardly over the end ofelement 24. The toggle springis confined under compression between andbears upon generally opposed abutments or spring seats 38, 39respectively furnished in bracket extension 37 and a stationary support41. These seats provide fulcrums upon which the spring rocks duringoperation of the armature mechanism. This spring 35 also functions tomaintain the armature 21 in an assembled relation in notch 16 byapplying a force to bracket 36, and hence -nism when disposed in theclosed or operated position shown in FIG. 4. The configuration of the Ufor the spring may also be designed for assisting in the achievement ofthis purpose.

I prefer to connect armature mechanism 21 and the movable contact 28 formovement together by a lost motion connection. That is to say, for apreselected initial travel of the armature from its fully open position,it should be free to move toward leg section 14 without movement beingimparted to movable contact 28. Thus, referring to FIG. 1, when thearmature mechanism 21 is in the fully open or unoperated position andthe movable contact 28 is in engagement with fixed contact 26, armatureend 25 is permitted to accelerate over a significant distance as itovercomes the bias of spring 35 before the armature makes a firm drivingconnection with contact 28. In order to accomplish this end, a U-shapedtab 44 may be stamped out from bracket 36 prior to its assembly ontoelement 24 and bent into an L-shaped extension such that a portion ofthe tab is arranged to overlie the extremity of spring blade 29 adjacentcontact 28 in a preselected spaced apart manner, denoted by letter a inFIG. 1.

Consequently, upon pivotal movement of armature end 25 downwardly towardleg section 14, away from its fully open position, the armature is freeto move distance a without interference from spring blade 29, gaining asignificant and a predetermined momentum before extension 44 engages thespring blade. This in turn produces an impact type engagement betweenthe armature mechanism 21 and the cantilever blade carrying contact 28(see FIG. 3) to impart sudden motion to that contact away from the fixedcontact. If the contacts resist opening, as might occur in a contactwelding condition, a high impact force will be developed and transmittedto contact 28 which overcomes the condition to insure an opening of thecontacts in response to downward movement of the armature.

FIG. 5 schematically shows the switch relay 10 just describedoperatively connected in a winding circuit of a single phase split phaseinduction motor having a conventional stator provided with a mainwinding 51 in parallel with a start winding 52. In particular, fixedcontact 26 of relay 10 is connected by a standard quick connect terminal53 to one side of the start winding which has its other side attached toterminal 54 of a three pronged unitary terminal post 55 (carried bysupport 30) which in turn, has another terminal 56 attached to one sideof a power supply line 57. Relay contact 28 is connected to the otherside of the power supply line 58 through terminals 59 and 60 of post 61and a conventional, manually operated control switch 62. Terminals 63and 64 respectively of posts 61 and 55 serially connect the main windingto the power supply lines. Coil 18 of the relay is energized throughconductors 65 and 66 which are attached by crimped connectors 67 betweenthe wire terminations of that coil and those of a sensing coil 68arranged in the start axis of the start winding 52.

Further features and advantages of relay 10 will become more apparentfrom a description of the manner in which the relay functions to controlthe circuit of start winding 52 during operation of the motor. With therelay components and manual switch disposed in the relative positionsshown in FIGS. 1 and 5, the start winding 52 and main winding 51 areenergized in parallel across power lines 5758. As the speed of the motorincreases, the voltage induced in sensing coil 68 becomes larger and is.75 applied to relay coil 18. This in turn causes an attraction on therelay armature element 24 proportional to the square of the appliedvoltage. It will be recalled from the previous explanation of the relaycomponents seen in FIG. 1 that the armature is held in its fully openposition solely by the bias of toggle spring 35. Thus, when the magneticforce of attraction on the armature created by the relay coil 18 andcore 11 exceeds the bias of this spring, armature end 25 will be puleddown toward the core without a corresponding movement of normally closedcontact 28 for a distance a by virtue of the lost motion connectionbetween these components.

The point at which the contacts are opened by the armature is in effecta so-called cutout speed of the motor. This may readily be calibrated inrelay by a screw 71 (FIG. 1) which is threadingly accommodated in asuitable hole in support 30 such that the end of the screw engagesbracket 36 to limit or control the exact dimension of a. Rotation ofscrew 71 results in a linear change in its position relative to thearmature 21 and de fines the fully open position of the armature.Consequently, the air gap dimension of the relay is regulated with aresulting control of the magnitude of the magnetic attraction across theair gap required to initiate downward motion of armature 21. It will beremembered that, as the distance across the air gap diminishes, theattraction on the armature or magnetic force becomes greater,accelerating the swinging motion of the armature toward the closedposition (zero air gap) evidenced in FIG. 4. Conversely, the springforce on armature 21 decreases as the air gap decreases. Thus, a smallchange in the calibrated air gap of relay 10 has a large effect in thevalue of the voltage at which the armature will be pulled down.

As the relative positions of the relay components seen in FIG. 3, a firmconnection is made between bracket extension 44 and the cantileverspring blade 29 of contact 28. The impact which is obtained in a simple,direct and highly effective way has already been discussed. Furtherswinging movement of armature end 25 towards the fully closed positionshown in FIG. 4, due to the progressively increasing magnetic attractionas the air gap decreases in size, overcomes the combined bias of spring29 and 35 to open contacts 26, 28, and the start winding circuit.

Under these circumstances, the motor operates under running conditionswith only the main winding 51 energized.

If the motor stalls for any reason and the speed is reduced until thevoltage induced in sensing coil 68 finally reaches 'a level suflicientlylow such that the magnetic attraction on the armature mechanism 21 isless than the combined or net spring bias or upward force placed uponarmature end 25 by springs 29 and 35, a cutback speed or condition isreached. At this time, springs 29 and 35 drive the armature to theposition seen in FIG. 3 and close contacts 26 and 28 to energize thestart winding 52. The.

motor begins one again to develop starting torque and, so long ascutback of the motor occurs between zero speed and the cutout speed,there is no need to accurately control the exact cutback speed at whichthe relay operates. However, if such control becomes desirable in theembodiment of FIGS. 1-5, accurate regulation may be accomplished bymerely adjusting the elevation of seat 39 in support bracket 41 relativeto opposed seat 37.

The following is one example of how the present invention has beencarried out in actual practice. Several relays 10 were constructed inaccordance with the illustrated embodiment of FIGS. 1 through 5inclusive and tested in a /3 horsepower, resistance split, single phasealternating current induction motor having four poles. The typicalspring force-deflection characteristic of these relays is set out in thegraph form of FIG. 6, with the spring forces biasing the armature beingplotted against the distance across the relay air gap.

From an inspection of FIG. 6, it will be observed that in the testedrelays of the exemplification the normal open position of the armature(with the contacts being closed) provides an air gap of approximately.075 inch A firm connection between the armature and spring 29 ofcontact 28 is made at an air gap of approximately .025. Above thispoint, only spring 35 applies a bias (curve A) to the armature. Thus,the armature 21 is allowed to accelerate over a distance a of about 0.05inch before it engages spring '29 to produce a significant momentum anddownward impact on contact 28 for opening the contacts. At an air gap of0.025 inch and smaller, both springs produce a net force on the armaturedenoted by the letter B.

As suggested by the graph of FIG. 6 the net spring forces with a smallair gap are less than those for a large air gap so the spring system isessentially a negative spring constant. Since the voltage induced insensing coil 68 after the contacts have been opened is merely /a to /2as great as that when the contacts are closed, just prior to theiropening, that is approximately under the same speed conditions, it isextremely desirable, if not essential, that the springs have a netnegative spring constant. In the embodiment of FIGS. 1-5, springs 29 and35 always have an aiding or augmenting rather than a buckingrelationship so that they also produce a continuous and positive bias onthe armature in a direction away from coil 11. Further, as seen in FIG.6, springs 29 ated satisfactorily well over 1,000,000 cycles with a -genFurther, they were erally uniform and quiet operation. relativelyinexpensive to fabricate, the components being easily assembledtogether, and the mechanical impact elements produced a highlysatisfactory, sudden separation of the contacts time and again in spiteof the fact that the relay components were not held to close toler-'ances. Moreover, the relays were compact and simple in construction andprovided a positive and consistently uniform motion of the movableswitch contact 28 and relay armature mechanism 21.

FIGS. 7, 8, and 9 illustrate a second embodiment of my invention inwhich identical parts to those shown in FIGS. l-5 inclusive areidentified by the same reference numbers. The switch relay of thissecond embodiment is generally denoted by numeral and like the firstembodirnent, has a magnetic core formed essentially with three spacedapart leg sections 81, 82, and 83, integrally united by yoke section 84.Outermost leg section 81a has a generally U-shaped notch 85 forpivotally mounting one end of a magnetizable, generally L-shaped,armature mechanism 91. Each of the other two leg sections accommodatessimilarly wound coils 92 and 93, serially connected, which togetheractuate armature 91. Suitable insulation 86 is disposed between eachcoil and the core for insulation reasons. FIG. 7, of legs 82 and 83 areeach provided with a U- shaped notch 87 in which is arranged a shadingcoil can be obtained with the same on a lower power or wattsdissipation. This thermally desirable condition is particularlybeneficial when my relay is utilized in electric equipment, such as theelectric motor of the exemplification where the overall operatingtemperature is a limiting factor on the type of components which may bein- I corporated in the equipment.

With respect to the construction of armature mechanism 91 of the secondembodiment, it is a single piece element having an enlarged, generallyrectangular slot -97 The upper edges, as viewed in extending from notch85 to a point adjacent leg portion 82a of the middle leg section 82. Agenerally U-shaped spring 101 has its ends held under compressionbetween a seat in bar projection 102, made integral with coil 95, and agenerally opposed seat formed in leg extension 98 of the armature, thatis, at its free end which is spaced outwardly from outermost leg section83. This spring forces engagement between wall 99 of armature slot 97and leg notch 85 for pivotal action and applies an upward bias to thefree end of armature 91, away from the core or leg section 83.

In the second embodiment, the movable contact 28 is biased to a normallyclosed position relative to fixed contact 26 by a cantilever spring 103which has its one end 104 secured to support 30 in the vicinity of, butabove, the fulcrum for the armature 91. The lost motion connectionbetween the armature and spring 103 is formed by projecting the free endof armature 91 through an enlarged rectangular opening 105 (FIG. 9)provided in a depending leg 106 of the cantilever spring 103. As thefree end of armature 91 is swung between the broken position shown inFIG. 7, its fully open position (contacts 26, 28 being closed) and itsfully closed position shown by the solid lines in FIGS. 7 and 9, thebottom of the armature in the spring opening 105 engages the bottom wallof the opening.

Like the first embodiment, between the fully open position of thearmature 91 and the point of engagement with the cantilever spring, themagnetic attraction on the armature must overcome only the bias of theU-shaped spring 101. Thus, the free end of the armature obtains asignificant momentum and provides a sudden, impacttype separation ofcontacts 26, 28 when engagement is made. As the air gap between the corelegs and armature 91 decreases between the point of engagement and fullyclosed position of the armature, this magnetic attraction is furtherincreased to overcome the bias of both springs. Essentially, then, thisoperation and spring system is similar to that of the FIGS. 16 and whenconnected in the circuit of FIG. 5, will operate in the mannerpreviously outlined for the first embodiment. Here, again, the resettingforces on the armature are the sum of the individual forces of the twosprings until the contacts are closed whereupon the U-shaped spring,applying a gradually increasing force on the armature, returns it to itsfully open position. However, in the second embodiment, although thecore and coils produce a greater magnetic attraction for a given coresize than the first embodiment, it is nonetheless slightly lessexpensive to manufacture. Note, for instance, the extremely simpleconstruction of armature 91. In addition, cutback of the relay 80 may bereadily calibrated by connecting a screw 109 to cantilever spring 103 bya threaded engagement indicated at 110 such that turning of the screwthrough support 30 will in efiect adjust the pivot of spring 103 andcontrol its deflection characteristic as required for a particularapplication.

From the foregoing, it will be appreciated that relay 80 incorporatesthe same desirable features and attributes ing leg sections integrallyjoined together at one end thereof by a yoke section, the end of one ofsaid legs remote from said yoke section pivotally mounting an armaturefor swinging the free end thereof toward and away from one of the otherleg sections respectively between closed and open armature positionstherewith, a coil accommodated on at least one leg section adapted to beenergized during operation of the motor for actuating said armature, agenerally U-shaped spring connected between the free end of saidarmature and a support and biasing the free end of said armature in adirection generally away from said other leg section, a first switchcontact spaced from side of said armature remote from said core, asecond contact movably mounted adjacent said first contact to provideclosed and open contact positions with respect to said first contact, asecond'spring normally biasing said second contact into engagement withsaid first contact, lost motion means connecting said armature andsecond contact for movement together, said generally U-shaped spring andsecond spring applying a bias to said armature when said contacts are ina nonengaging relation with the net spring force on said armature beinggenerally greater when said contacts are closing than when said contactsare in the open position, the lost motion means between said armatureand second contact being disengaged when said first and second contactsare in the closed position and becoming engaged with an impact as thearmature overcomes the bias of said springs, gains momentum to causesudden separation of said contacts and drives said second contact intothe open contact position as the free end of the armature swings towardthe closed armature position.

2. A switch relay having normally closed contacts for use in an electricmotor, the relay comprising a core formed of magnetic material, anarmature pivotally mounted adjacent said core for swinging the free endthereof toward and away from the core respectively between closed andopen armature positions, a winding accommodated on said core adapted tobe energized during operation of the motor for actuating said armature,a generally U-shaped spring connected to the free end of said armatureand to a support, said spring continuously biasing the free end of saidarmature in a direction generally away from said core, a first switchcontact spaced from the side of said armature remote from said core, asecond contact movably mounted adjacent said first contact to provideopen and closed contact positions While in accordance with the PatentStatutes, I have described what at present is considered to be thepreferred embodiments of my invention, it will be obvious to thoseskilled in the art that numerous changes and modifications may be madetherein without departing from the invention and it is therefore aimedin the appended claims to cover all such equivalent variations as fallwithin the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent to the UnitedStates is:

1. A switch relay having normally closed contacts for use in an electricmotor, the relay comprising a core formed of magnetic material having atleast two upstandwith respect to said first contact, a second springnormally biasing said second contact into engagement with said firstcontact, calibrating means engaging said second spring for regulatingthe bias thereof, said armature having a lost motion connection withsaid second contact, calibrating means for controlling the lost motionin said connection between said armature and said second contact, saidgenerally U-shaped and second springs applying a bias to said armaturewhen said contacts are in a nonengaging relation with the net springforce on said armature being generally greater when said contacts areclosing than when said contacts are in the open position, said lostmotion connection between said armature and second contact beingdisengaged when said first and second contacts are in the closedposition and becoming engaged with an impact as the armature overcomesthe bias of said springs to cause sudden separation of said contacts andto drive the second contact into the open contact position as the freeend of the armature swings toward the closed armature position.

3. A switch relay having normally closed contact comprising a coreformed of magnetic material, an armature pivotally mounted adjacent saidcore for swinging a free end thereof toward and away from the corerespectively between closed and open armature positions,electromagneticmeans adapted to be energized for actuating saidarmature, a generally U-shaped spring connected between said free end ofsaid armature and a support,

said spring continuously biasing the free end of said armature in adirection generally away from said core,

first switch contact means spaced from the side of saidv armature remotefrom said core, second switch contact means including a cantileverspring having one end firmly supported, the free end of said cantileverspring projecting between said armature and said first contact means andnormally biasing said second contact means into engagement with saidfirst contact means, lost motion means connecting said armature andcantilever spring for joint movement from said closed contact positionto said open contact position, said U-shaped spring and cantileverspring applying a bias to said armature when said first and secondcontact means are in a nonengaging relation, said anmature'and saidcantilever spring being disengaged when the free end of the armature isin the open position, said armature and cantilever spring becomingfirmly connected as said armature overcomes the bias of both springs,gains momentum and makes impact with said cantilever spring to cause asudden separation of said first and second contact means, said lostmotion means effecting a greater armature travel during itsdisengagement from said cantilever spring'than during the connection ofsaid armature and cantilever spring for movement together.

4. A switch relay comprising a core formed of magnetic material havingat least two upstanding leg sections, an armature pivotally mounted forswinging a free end thereof toward and away from one of the leg sectionsand defining an air gap therewith, a winding accommodated on at leastone leg section adapted to be energized for actuating said armature, afirst spring connected between said armature and a support and biasingthe free end of said armature away from said one leg section, a firstswitch contact spaced from said armature, a cantilever spring having oneend rigidly mounted and carrying a second contact for movement betweenclosed and open contact positions relative to said first switch contact,said cantilever spring biasing said second contact toward said firstcontact, means connecting said armature and said cantilever spring forconcurrent movement, said first spring and cantilever spring togetherdefining a net negative spring constant and applying a bias to the freeend of said armature when said contacts are in a nonengaging relation,the net spring force on said armature being generally greater when saidrelay air gap is maximum than when said air gap is a minimum.

5.'A switch relay comprising a core formed of magnetic material, anarmature pivotally mounted for swing 'ing the freeend thereof toward andaway from said core and defining an air gap therewith, electromagneticmeans for actuating said armature, a first snap acting spring connectedto said armature and to a stationary support and continuously biasingthe free'end of said armature in a direction generally away from saidcore, a first switch contact spaced from said armature, a second contactmovably disposed adjacent said first contact, a second spring connectedto said second contact for biasing it toward said first contact, saidfirst and second springs together defining a net negative springconstant, calibrating means for regulating the bias of at least saidfirst spring, and means connecting said armature and said second contactfor joint movement, said first and second springs applying a bias tosaid armature when said contacts are in a nonengaging relation.

6. A switch relay having normally closed contacts for use in an electricmotor, the relay comprising a core formed of magnetic material, anarmature pivotally mounted adjacent said core for swinging the free endthereof toward and away from the core to define an air gap therewith, awinding accommodated on said core adapted to be energized duringoperation of the motor for actuating said armature, a generally U-shapedspring connected to the free end of said armature and to a sup port,said spring-continuously biasing the free end of I said armature awayfrom said core, a first switch contact spaced from the side of saidarmature remote from said V core, a second contact movably mountedadjacent said first contact to provide open and closed contact positionswith respect to said first contact, a second spring normally biasingsaid second contact into engagement with said first contact, calibratingmeans engaging said second spring for regulating the bias thereof, saidarmature having a lost motion connection with said second contact,calibrating means for controlling the lost motion in said connectionbetween said armature and said second contact, said generally U-shapedand second springs applying a bias to said armature when said contactsare in a nonengaging relation with the net spring force on said armaturebeing generally greater when said relay air gap is maximum than whensaid air gap is a minimum, said lost motion connection between saidarmature and second contact being disengaged when said first and secondcontacts are in the closed position and becoming engaged with an impactas the armature overcomes the bias of said springs and to cause suddenseparation of said contacts.

7. A switch relay having normally closed contacts for use in an electricmotor, the relay comprising a core formed of magnetic material having atleast two leg sections joined together at one end thereof by a yokesection, the end of one of said legs remote from said yoke sectionpivotally mounting an armature for swinging the free end thereof towardand away from one of the outermost leg sections to define an air gaptherewith, an electromagnetic winding accommodated on at least one legsection adapted to be energized during operation of the motor foractuating said armature, a generally U-shaped spring connected to thefree end of said armature and to a support, said spring continuouslybiasing said armature in a direction generally away from said oneoutermost leg section, a first switch contact spaced from the side ofsaid armature remote from said core, a second contact carried by acantilever spring between said first contact and said armature formovement between open and closed contact positions with respect to saidfirst contact, said cantilever spring having one end firmly supportedwith the other end projecting generally toward the pivot of saidarmature and normally biasing said second contact into engagement withsaid first contact, said armature including an extension overlying apart of said cantilever spring adjacent said second contact, saidU-shaped and cantilever springs applying a bias to said armature whensaid contacts are in a nonengaging relation with the springs togetherdefining a net negative spring constant, said armature extension beingin spaced relation with said cantilever spring when said first andsecond contacts are in the closed position and engaging said cantileverspring with an impact as said armature overcomes the bias of bothsprings and gains momentum to cause a sudden separation of saidcontacts.

8. A switch relay having normally closed contacts for use in an electricmotor, the relay comprising a core formed of magnetic material having atleast two upstanding leg sections joined together at one end thereof bya yoke section, a generally L-shaped armature having the end of thelongest leg pivotally attached to the end of one of said legs remotefrom said yoke section for swinging the free end thereof toward and awayfrom one of the outermost leg sections to define an air gap therewith,an electromagnetic winding accommodated on at least one leg sectionadapted to be energized during operation of the motor for actuating saidarmature, a generally U- shaped spring connected between the shorter legof said armature and a support, said spring biasing the free end of saidarmature in a direction generally away from said one outermost legsection, a first switch contact spaced from the sideof said armatureremote from said core, a cantilever spring carrying a second contact andnormally biasing said second contact into engagement with said firstcontact, said cantilever spring having an extension formed with a slotat its free end, said armature projecting through said slot and making alost motion connection therewith, said U-shaped spring and cantileverspring conjointly applying a bias to said armature when said contactsare in a nonengaging relation with the springs together defining a netnegative spring constant, said spring extension and armature having aloose connection when said first and second contacts are in the closedposition, said armature engaging said cantilever spring extension withan impact to make a firm connection therewith as said armature overcomesthe bias of both springs and gains momentum to cause a sudden separationof said contacts.

9. A switch relay comprising a core formed of magnetic material, anarmature pivotally mounted for swinging a free end thereof toward andaway from said core and defining an air gap therewith, electromagneticmeans for actuating said armature, a first spring connected to saidarmature and to a support, said spring applying a force on said armatureto bias the free end of said armature in a direction generally away fromsaid core, a first switch contact spaced from said armature, a secondcontact disposed adjacent said first contact and movable between closedand open contact positions relative to said first contact, a secondspring connected to said second contact for biasing it toward saidclosed contact position, and means connecting said armature and saidsecond contact for joint movement between said closed and open contactpositions, the biasof said first spring progressively increasing as saidarmature air gap increases for closing said contacts, said second springapplying a gradually decreasing bias to said armature as said secondcontact moves from said open to said closed contact positions. 7

10. The switch relay of claim 9 in which the spring force applied tosaid armature by said second spring is greater than the spring force'ofsaid first spring at the open contact position but is less than thespring force of said first spring at the closed contact position, saidfirst and second springs together defining a net negative springconstant.

11. The switch relay of claim 3 in which said armature includes amagnetic element and said lost. motion means comprises a bracket mountedto the side of said element remote from the core, said bracket having anL-shaped extension bent away from said element and overlying the freeend of said cantilever spring, said L-shaped extension being disengagedwith said cantilever spring when said armature is in the open armatureposition.

12. The switch relay of claim 3 in which said cantilever spring includesa depending extension at the free end thereof, said lost motion meanscomprises an enlarged slot formed in said extension, with a portion ofsaid armature projecting through said enlarged slot, said extension andarmature having a loose connection when said first and second contactmeans are in engagement with one another to provide lost motion for saidlost motion means.

References Cited by the Examiner UNITED STATES PATENTS 2,585,684 2/ 1952Roggenstein 20087 3,007,062 10/1961 Teasell 3071 12 3,165,607 1/1965Hogan 200-87 FOREIGN PATENTS 833,686 4/1960 Great Britain.

' References Cited by the Applicant UNITED STATES PATENTS 1,621,056 3/1927 Bradshaw.

2,285,936 6/1942 Mishelevich. 2,292,497 8/ 1942 Vradenburgh.

2,326,760 8/1943 Clare. 2,527,220 10/ 1950 Hughes.

2,808,553 10/1957 Clark. 2,892,050 6/ 1959 Fisher.

2,896,041 7/ 1959 Schwancke.

2,897,308 7/ 1959 Fergus.

BERNARD A. GILHEANY, Primary Examiner.

J. J. BAKER, Assistant Examiner.

1. A SWITCH RELAY HAVING NORMALLY CLOSED CONTACTS FOR USE IN AN ELECTRICMOTOR, THE RELAY COMPRISING A CORE FORMED OF MAGNETIC MATERIAL HAVING ATLEAST TWO UPSTANDING LEG SECTIONS INTEGRALLY JOINED TOGETHER AT ONE ENDTHEREOF BY A YOKE SECTION, THE END OF ONE OF SAID LEGS REMOTE FROM SAIDYOKE SECTION PIVOTALLY MOUNTING AN ARMATURE FOR SWINGING THE FREE ENDTHEREOF TOWARD AND AWAY FROM ONE OF THE OTHER LEG SECTIONS RESPECTIVELYBETWEEN CLOSED ADN OPEN ARMATURE POSITIONS THEREWITH, A COILACCOMMODATED ON AT LEAST ONE LEG SECTION ADAPTED TO BE ENERGIZED DURINGOPERATION OF THE MOTOR FOR ACTUATING SAID ARMATURE, A GENERALLY U-SHAPEDSPRING CONNECTED BETWEEN THE FREE END OF SAID ARMATURE AND A SUPPORT ANDBIASING THE FREE END OF SAID ARMATURE IN A DIRECTION GENERALLY AWAY FROMSAID OTHER LEG SECTION, A FIRST SWITCH CONTACT SPACED FROM SIDE OF SAIDARMATURE REMOTE FROM SAID CORE, A SECOND CONTACT MOVABLY MOUNTEDADJACENT SAID FIRST CONTACT TO PROVIDE CLOSED AND OPEN CONTACT POSITIONSWITH RESPECT TO SAID FIRST CONTACT, A SECOND SPRING NORMALLY BIASINGSAID SECOND CONTACT INTO ENGAGEMENT WITH SAID FIRST CONTACT, LOST MOTIONMEANS CONNECTING SAID ARMATURE AND SECOND CONTACT FOR MOVEMENT TOGETHER,SAID GENERALLY U-SHAPED SPRING AND SECOND SPRING APPLYING A BIAS TO SAIDARMATURE WHEN SAID CONTACTS ARE IN A NONENGAGING RELATION WITH THE NETSPRING FORCE ON SAID ARMATURE BEING GENERALLY GREATER WHEN SAID CONTACTSARE CLOSING THAN WHEN SAID CONTACTS ARE IN THE OPEN POSITION, THE LOSTMOTION MEANS BETWEEN SAID ARMATURE AND SECOND CONTACT BEING DISENGAGEDWHEN SAID FIRST AND SECOND CONTACTS ARE IN THE CLOSED POSITION ANDBECOMING ENGAGED WITH AN IMPACT AS THE ARMATURE OVERCOMES THE BIAS OFSAID SPRINGS, GAINS MOMENTUM TO CAUSE SUDDEN SEPARATION OF SAID CONTACTSAND DRIVES SAID SECOND CONTACT INTO THE OPEN CONTACT POSITION AS THEFREE END OF THE ARMATURE SWING TOWARD THE CLOSED ARMATURE POSITION.